The present invention relates generally to an improved apparatus and method for making clear or transparent ice, and more specifically, to an apparatus and method for making clear or transparent ice in a variety of geometric shapes and which can be implemented in commonly available refrigeration/freezer equipment.
Typical household and commercial refrigeration systems include separate refrigerator and freezing compartments. Ice cubes may be formed manually or automatically in various conventionally known manners utilizing the freezing compartment of such refrigeration and freezing equipment. As is commonly known, making ice typically involves filling a tray with individual cube molds, either fixed to or formed as part of an ice tray, with water and placing the ice tray in a freezer compartment having an ambient air temperature below 32° F. The water in the tray begins to freeze and solidify from all sides and surfaces (including the top water surface which is directly exposed to the freezing air) then in and through the remaining volume of water occupying the cube mold since the exterior peripheral cube surfaces freeze first. Impurities and gases contained within the water to be frozen are trapped in the solidified ice cube during the freezing process, commonly near the center and/or the bottom surface of the ice cube, due to their inability to escape as a result of the freezing liquid to solid phase change of the ice cube surfaces. Once the water in the tray is frozen solid, the ice tray is removed from the freezer compartment and each individual ice cube formed in the tray is removed from the individual cube molds and either placed in a beverage to cool the temperature of the beverage or placed in a storage bin in the freezer compartment for later use.
As highlighted above, such known ice cube formation apparatus and methods produce opaque or “clouded” ice cubes which result from the entrapment of suspended and dissolved solids, liquids and gases that become trapped within the frozen ice cube during the freezing process. The opaque appearance of the ice cubes is generally aesthetically displeasing. Likewise, suspended and dissolved impurities that are entrapped in the frozen ice cube are released into the beverage or foodstuff being cooled by the ice cube as the ice cube melts. Moreover, the frozen structure of these impurities maximizes the interstitial surface area of the ice cube thereby increasing the melt rate of the ice cube and further watering down the beverage being cooled by the ice cube.
Commercially available clear icemakers are known in the art that require complex mechanical and thermodynamic processes to form clear ice. For example, the apparatus disclosed in U.S. Pat. No. 3,952,539, requires the use of metal inserts with heating elements to prevent freezing of the ice cube at the bottom of each ice grid cavity to enable the production of clear ice cubes and their removal from the tray. The clear ice tray disclosed in U.S. Pat. No. 6,357,720 requires the use of an ice mold with sidewalls and a closed mold bottom that must be air permeable for venting air bubbles that are produced in the water during the formation of solid ice cubes. The method and apparatus disclosed in U.S. Pat. No. 6,357,720 is also limited in its ability to produce clear ice cubes in that the gases vented during the freezing process must be diffused through the permeable sidewalls and the mold bottom at a faster rate than the liquid-to-solid phase change rate occurring in the ice mold. However, the suspended and dissolved solids and liquids in the water freezing in the molds are not removed or liberated and remain in the resulting ice cubes. Another drawback of these known apparatii and methods for producing clear ice concerns their requirement of electro-mechanical energy inputs and assemblies, and/or specific construction materials (e.g. air permeable) that may only be formed and produced using technical construction methods and equipment in order to function and produce clear ice. Moreover, they fail to produce a clear ice product as they are generally focused and drawn to the removal of a specific contaminant, such as gas bubbles or suspended solids, versus the removal of the combination of suspended and dissolved liquids, solids and gases which exist in unfrozen water and prevent the formation of clear ice.
Accordingly, there is a need in the art for an apparatus and method for making clear or transparent ice that acts to substantially reduce or eliminate the entrapment of solids and gases during the production of ice cubes. There is a need in the art for a simple, inexpensive apparatus and method for producing clear or transparent ice which does not require the use or purchase of complex mechanical/electro-mechanical equipment and processes, and which may be implemented using conventional and readily available refrigeration and/or freezing appliances and materials. There is a need in the art for an easily configurable apparatus and method allowing for the production of a variety of ice shapes that do not require intensive equipment modification or labor for implementation and production.